Studies in allogeneic marrow recipients have shown that donor stromal cells do not engraft during marrow transplantation, indicating 1) that residual host stromal cells are responsible for supporting hematopoiesis and 2) that acquired damage to the irreplaceable host stroma could play a significant role in graft failure. This project is designed to investigate two potential mechanisms of stromal cell damage that require an autologous transplant setting for proper analysis. First, the effects of prior treatment and pretransplant conditioning regimens on stromal cell function will be determined. Stromal cell cultures will be established from patient marrow before and at variable times after conditioning and transplantation and characterized for cellular composition, factor production and progenitor binding. Laboratory techniques will include immune histochemistry to define cellular composition, northern analysis of isolated RNA to determine factor production, and the preparation and growth of highly enriched progenitor populations to assay progenitor binding. Data will be obtained from approximately 30 patients per year and then analyzed in regard to the patient's drug and total body irradiation exposure. The second study will determine whether various stromal and progenitor components can be infected with cytomeglovirus (CMV) and, once infected, how infection may interfere with function. Cultures established from normal marrow will be infected with CMV. infected and uninfected stromal cell cultures will be evaluated for cellular composition, factor production and progenitor binding. The presence of viral genome in distinct cell populations will be determined by polymerase chain reaction (pcr), ani viral protein by immune histochemistry. The demonstration of cytolysis of chromated infected and uninfected stromal cells by autologous lymphocytes will determine if cytolytic mechanisms directed at virus encoded antigens contribute to stromal cell damage of CMV infected targets. The ability of various cell populations to become infected and the consequences of that infection will be analyzed in regard to HLA antigens to determine how various alleles may contribute to this process. The data obtained from these studies should help define how stromal cell damage contributes to poor graft function and possibly suggest therapeutic strategies to remedy this complication.